Outline

Objective

To analyse the relation between the partial pressure of brain tissue oxygen (PtiO2) and regional cerebral blood flow (rCBF).

Methods

In 8 patients after severe aneurysmal subarachnoid haemorrhage (SAH, n=5) and severe traumatic brain injury (TBI, n=3) simultaneous continuous monitoring of PtiO2 and rCBF was performed. Parameters were measured using a flexible polarographic PtiO2-probe and a newly developed thermal diffusion microprobe. The mean duration of monitoring was 10 days. Statistical analysis of the data was made using linear regression.

Results

Regarding the whole monitoring period, the data suggested a linear relation between rCBF and PtiO2. In 72 % of 400 analysed intervals of 30 minutes duration, a strong correlation between rCBF and PtiO2 existed (r > 0,6) and in 19 % of intervals a less strong, but statistically still significant correlation was observed (0,3 < r < 0,6). During the remaining 9 % no correlation was found (r < 0,3).

Conclusions

This study demonstrated that changes of PtiO2 are induced by simultaneous changes of rCBF in more than 90 % of episodes. Other factors influencing PtiO2, such as arterial oxygen content, may be of secondary importance.